The objective of this proposal is to maintain a closed specific pathogen free (SPF) rhesus macaque supply and breeding colony program at the Sabana Seca Field Station of the Caribbean Primate ResearchCenter (CPRC). The founding stock of genetically-characterized Indian-origin monkeys will be donated by CPRC and will consist of approximately 457 SPF rhesus macaques. Animals from this closed colony will be housed in reproduction corncribs, and will be quarterly tested for the presence of four target viruses (Herpes B, STLV-1, SIV and SRV). A panel of highly polymorphic genetic markers will be used to characterize the colony and to optimize the structure of breeding groups, maximizing the level of their genetic heterogeneity. By year five, the program will produce a total estimated offspring of 833 SPF rhesus macaques which will help meet the increased demand for these animals. At the end of this grant, it is expected that this program will produce about 210 animals/year, thus attaining self-sufficiency. CPRC will continue to make significant contributions to AIDS and to other research programs by providing .high quality and healthy SPF rhesus monkeys to NIH-sponsored research initiatives.